Method for transmitting/receiving signal and device therefor

ABSTRACT

The present invention relates to a wireless communication system. More particularly, the present invention relates to a method for transmitting uplink control information and a device therefor, the method comprising the steps of: forming a plurality of serving cells each having different UL-DL configurations; receiving one or more signals requiring a HARQ-ACK response from M(M&gt;1) number of subframes; and executing the process for transmitting the HARQ-ACK response to the one or more signals in a specific subframe corresponding to the M number of subframes, wherein, only when the specific subframe is set as an uplink in all of the plurality of serving cells, the HARQ-ACK response to the one or more signals are transmitted through the specific subframe.

TECHNICAL FIELD

The present invention relates to a wireless communication system, andmore specifically, to a method for transmitting/receiving a signal in aTDD (Time Division Duplex) system and a device for the same.

BACKGROUND ART

Wireless communication systems have been widely deployed to providevarious types of communication services including voice and dataservices. In general, a wireless communication system is a multipleaccess system that supports communication among multiple users bysharing available system resources (e.g. bandwidth, transmit power,etc.) among the multiple users. The multiple access system may adopt amultiple access scheme such as Code Division Multiple Access (CDMA),Frequency Division Multiple Access (FDMA), Time Division Multiple Access(TDMA), Orthogonal Frequency Division Multiple Access (OFDMA), or SingleCarrier Frequency Division Multiple Access (SC-FDMA).

DISCLOSURE Technical Object

An object of the present invention is to provide a method and apparatusfor efficiently transmitting/receiving a signal in a wirelesscommunication system supporting TDD. Another object of the presentinvention is to provide a method and apparatus for efficientlytransmitting/receiving a signal in a wireless communication systemsupporting multiple carriers and TDD.

The technical objects achieved by the present invention are not limitedto the above technical problems and those skilled in the art mayunderstand other technical objects from the following description.

Technical Solution

In an aspect of the present invention, a method for transmitting uplinkcontrol information by a user equipment (UE) in a TDD (Time DivisionDuplex) wireless communication system is disclosed herein, the methodcomprising: configuring a plurality of serving cells having differentUL-DL (Uplink-Downlink) configurations; receiving one or more signalsrequiring a HARQ-ACK (Hybrid Automatic Repeat request-Acknowledgement)response in M (M≧1) subframes; and performing a process for transmittingthe HARQ-ACK response to the one or more signals in a specific subframecorresponding to the M subframes, wherein the HARQ-ACK response to theone or more signals is transmitted through the specific subframe onlywhen the specific subframe is configured as uplink in all the pluralityof serving cells.

In an another aspect of the present invention, a user equipment (UE)configured to transmit uplink control information a TDD (Time DivisionDuplex) wireless communication system is disclosed herein, the UEcomprising an RF unit and a processor, wherein the processor isconfigured to configure a plurality of serving cells having differentUL-DL (Uplink-Downlink) configurations, to receive one or more signalsrequiring a HARQ-ACK (Hybrid Automatic Repeat request-Acknowledgement)response in M (M≧1) subframes, and to perform a process for transmittingthe HARQ-ACK response to the one or more signals in a specific subframecorresponding to the M subframes, wherein the HARQ-ACK response to theone or more signals is transmitted through the specific subframe onlywhen the specific subframe is configured as uplink in all the pluralityof serving cells.

The M subframes corresponding to the specific subframe may be determinedby a DASI (Downlink Association Set Index) of a UL-DL configurationconfigured for a serving cell having the largest number of DL subframes.

The HARQ-ACK response to the one or more signals may be transmittedthrough a PUCCH (Physical Uplink Control Channel) of a primary cell fromamong the plurality of serving cells.

The UE may generate a HARQ-ACK payload including the HARQ-ACK responseto the one or more signals, wherein a size of the HARQ-ACK payload isdetermined by the number of serving cells and a value of M, wherein,when a serving cell having a subframe configured as uplink from amongthe M subframes is present, a HARQ-ACK response to the UL subframe ofthe serving cell is not included in the HARQ-ACK payload.

When the M subframes include a specific subframe which is not configuredas downlink for all the plurality of serving cells, decoding of a PDSCH(Physical Downlink Shared Channel) may be skipped in the specificsubframe and a HARQ-ACK response corresponding to the specific subframemay not be included in the HARQ-ACK payload.

The one or more signals requiring the HARQ-ACK response may include aPDSCH signal or a PDCCH (Physical Downlink Control Channel) signalindicating SPS (Semi-Persistent Scheduling) release.

Advantageous Effects

According to the present invention, a signal can be efficientlytransmitted/received in a wireless communication system supporting TDD.Furthermore, a signal can be efficiently transmitted/received in awireless communication system supporting multiple carriers and TDD.

The effects achieved by the present invention are not limited to theabove-described effects and other effects which are not described hereinwill become apparent to those skilled in the art from the followingdescription.

DESCRIPTION OF DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention, illustrate embodiments of the inventionand together with the description serve to explain the principle of theinvention. In the drawings:

FIG. 1 illustrates a radio frame structure;

FIG. 2 illustrates a resource grid of a downlink slot;

FIG. 3 illustrates a downlink subframe structure;

FIG. 4 illustrates an uplink subframe structure;

FIGS. 5 and 6 illustrate TDD UL ACK/NACK transmission timing in a singlecell case;

FIGS. 7 and 8 illustrate TDD PUSCH transmission timing in a single cellcase;

FIGS. 9 and 10 illustrate TDD DL ACK/NACK transmission timing in asingle cell case;

FIG. 11 illustrates a carrier aggregation (CA) communication system;

FIG. 12 illustrates scheduling in case of aggregation of a plurality ofcarriers;

FIGS. 13 and 14 are tables for illustrating TDD UL ACK/NACK transmissiontiming according to an embodiment of the present invention;

FIGS. 15 and 16 are tables for illustrating TDD DL ACK/NACK transmissiontiming according to an embodiment of the present invention;

FIGS. 17 to 20 are tables for illustrating nested carrier aggregationaccording to an embodiment of the present invention; and

FIG. 21 illustrates a base station (BS) and user equipment (UE)applicable to an embodiment of the present invention.

BEST MODE

Embodiments of the present invention are applicable to a variety ofwireless access technologies such as Code Division Multiple Access(CDMA), Frequency Division Multiple Access (FDMA), Time DivisionMultiple Access (TDMA), Orthogonal Frequency Division Multiple Access(OFDMA), and Single Carrier Frequency Division Multiple Access(SC-FDMA). CDMA can be implemented as a radio technology such asUniversal Terrestrial Radio Access (UTRA) or CDMA2000. TDMA can beimplemented as a radio technology such as Global System for Mobilecommunications (GSM)/General Packet Radio Service (GPRS)/Enhanced DataRates for GSM Evolution (EDGE). OFDMA can be implemented as a radiotechnology such as Institute of Electrical and Electronics Engineers(IEEE) 802.11 (Wireless Fidelity (Wi-Fi)), IEEE 802.16 (Worldwideinteroperability for Microwave Access (WiMAX)), IEEE 802.20, EvolvedUTRA (E-UTRA). UTRA is a part of Universal Mobile TelecommunicationsSystem (UMTS). 3^(rd) Generation Partnership Project (3GPP) Long TermEvolution (LTE) is a part of Evolved UMTS (E-UMTS) using E-UTRA,employing OFDMA for downlink and SC-FDMA for uplink. LTE-Advanced(LTE-A) is an evolution of 3GPP LTE.

While the present invention is described focusing on 3GPP LTE/LTE-A forclarity, this is purely exemplary and thus should not be construed aslimiting the present invention.

FIG. 1 illustrates a radio frame structure.

Referring to FIG. 1, a radio frame used in 3GPP LTE(−A) has a length of10 ms (307200T_(s)) and includes 10 subframes of equal size. The 10subframes in the radio frame may be numbered. Here, T_(s) denotessampling time and is represented as T_(s)=1/(2048*15 kHz). Each subframehas a length of 1 ms and includes two slots. 20 slots in the radio framemay be sequentially numbered from 0 to 19. Each slot has a length of 0.5ms. A transmission time for a subframe is defined as a transmission timeinterval (TTI). Time resources may be distinguished by a radio framenumber (or radio frame index), a subframe number (or subframe index), aslot number (or slot index), and etc.

The radio frame may be configured differently according to a duplexmode. In a FDD (Frequency Division Duplex) mode, downlink transmissionand uplink transmission are distinguished by frequency, and thus theradio frame includes only one of a downlink subframe and an uplinksubframe in a specific frequency band. In a TDD (Time Division Duplex)mode, downlink transmission and uplink transmission are distinguished bytime, and thus the radio frame includes both a downlink subframe and anuplink subframe in a specific frequency band.

Particularly, FIG. 1 shows a radio frame structure for TDD, used in 3GPPLTE(−A). Table 1 shows UL-DL (Uplink-Downlink) configurations of eachsubframe in a radio frame in the TDD mode.

TABLE 1 Downlink- to- Uplink Uplink- Switch- downlink point Subframenumber configuration periodicity 0 1 2 3 4 5 6 7 8 9 0 5 ms D S U U U DS U U U 1 5 ms D S U U D D S U U D 2 5 ms D S U D D D S U D D 3 10 ms  DS U U U D D D D D 4 10 ms  D S U U D D D D D D 5 10 ms  D S U D D D D DD D 6 5 ms D S U U U D S U U D

In Table 1, D denotes a downlink subframe, U denotes an uplink subframeand S denotes a special subframe. The special subframe includes a DwPTS(Downlink Pilot TimeSlot), GP (Guard Period), and UpPTS (Uplink PilotTimeSlot). DwPTS is a period reserved for downlink transmission andUpPTS is a period reserved for uplink transmission. Table 2 shows aspecial subframe configuration.

TABLE 2 Normal cyclic prefix in downlink Extended cyclic prefix in UpPTSdownlink Normal UpPTS cyclic Extended Normal Extended Special prefixcyclic cyclic cyclic subframe in prefix prefix in prefix inconfiguration DwPTS uplink in uplink DwPTS uplink uplink 0  6592 · T_(s)2192 · T_(s) 2560 · T_(s)  7680 · T_(s) 2192 · T_(s) 2560 · T_(s) 119760 · T_(s) 20480 · T_(s) 2 21952 · T_(s) 23040 · T_(s) 3 24144 ·T_(s) 25600 · T_(s) 4 26336 · T_(s)  7680 · T_(s) 4384 · T_(s) 5120 ·T_(s) 5  6592 · T_(s) 4384 · T_(s) 5120 · T_(s) 20480 · T_(s) 6 19760 ·T_(s) 23040 · T_(s) 7 21952 · T_(s) — — — 8 24144 · T_(s) — — —

FIG. 2 illustrates a resource grid of a downlink slot.

Referring to FIG. 2, a downlink slot includes a plurality of OFDMsymbols in the time domain. One downlink slot may include 7(6) OFDMsymbols, and one resource block (RB) may include 12 subcarriers in thefrequency domain. Each element on the resource grid is referred to as aresource element (RE). One RB includes 12×7(6) REs. The number N_(RB) ofRBs included in the downlink slot depends on a downlink transmissionbandwidth. The structure of an uplink slot may be the same as that ofthe downlink slot except that OFDM symbols are replaced by SC-FDMAsymbols.

FIG. 3 illustrates a downlink subframe structure.

Referring to FIG. 3, a maximum of three (four) OFDM symbols located in afront portion of a first slot within a subframe correspond to a controlregion to which a control channel is allocated. The remaining OFDMsymbols correspond to a data region to which a physical downlink sharedchancel (PDSCH) is allocated. A PDSCH is used to carry a transport block(TB) or a codeword (CW) corresponding to the TB. The transport blockmeans a data block transmitted from a MAC (Medium Access Control) layerto a PHY (Physical) layer via a transport channel. The codewordcorresponds to a coded version of a transport block. The relationshipbetween the transport block and the codeword depends on swapping. In thespecification, the PDSCH, transport block and codeword areinterchangeably used. Examples of downlink control channels used inLTE(−A) include a physical control format indicator channel (PCFICH), aphysical downlink control channel (PDCCH), a physical hybrid ARQindicator channel (PHICH), etc. The PCFICH is transmitted at a firstOFDM symbol of a subframe and carries information regarding the numberof OFDM symbols used for transmission of control channels within thesubframe. The PHICH is a response to uplink transmission and carries aHARQ-ACK (Hybrid Automatic Repeat reQuest Acknowledgment) signal. AHARQ-ACK response includes a positive ACK (simply, ACK), a negative ACK(Negative ACK), DTX (Discontinuous Transmission) or NACK/DTX. Here,HARQ-ACK is used interchangeably with HARQ ACK/NACK or ACK/NACK.

Control information transmitted via a PDCCH is referred to as downlinkcontrol information (DCI). The DCI includes resource allocationinformation for a UE or UE group and other control information. Forexample, the DCI includes uplink/downlink scheduling information, anuplink transmit (Tx) power control command, etc. Information content oftransmission modes and DCI formats for configuring a multi-antennatechnology are as follows.

Transmission Mode

-   -   Transmission mode 1: Transmission from a single base station        antenna port    -   Transmission mode 2: Transmit diversity    -   Transmission mode 3: Open-loop spatial multiplexing    -   Transmission mode 4: Closed-loop spatial multiplexing    -   Transmission mode 5: Multi-user MIMO    -   Transmission mode 6: Closed-loop rank-1 precoding    -   Transmission mode 7: Transmission using UE-specific reference        signals

DCI Format

-   -   Format 0: Resource grants for the PUSCH (Physical Uplink Shared        Channel) transmissions (uplink)    -   Format 1: Resource assignments for single codeword PDSCH        (Physical Downlink Shared Channel) transmissions (transmission        modes 1, 2 and 7)    -   Format 1A: Compact signaling of resource assignments for single        codeword PDSCH (all modes)    -   Format 1B: Compact resource assignments for PDSCH using rank-1        closed loop precoding (mod 6)    -   Format 1C: Very compact resource assignments for PDSCH (e.g.        paging/broadcast system information)    -   Format 1D: Compact resource assignments for PDSCH using        multi-user MIMO (mode 5)    -   Format 2: Resource assignments for PDSCH for closed-loop MIMO        operation (mode 4)    -   Format 2A: Resource assignments for PDSCH for open-loop MIMO        operation (mode 3)    -   Format 3/3A: Power control commands for PUCCH (Physical Uplink        Control Channel) and PUSCH with 2-bit/1-bit power adjustments

As described above, the PDCCH may carry transport format and resourceallocation information of a downlink shared channel (DL-SCH), transportformat and resource allocation information of an uplink shared channel(UL-SCH), paging information on a paging channel (PCH), systeminformation on the DL-SCH, resource allocation information of anupper-layer control message such as a random access response transmittedon a PDSCH, a set of Tx power control commands for individual UEs withina UE group, a Tx power control command, information indicatingactivation of a voice over IP (VoIP), etc. A plurality of PDCCHs may betransmitted within a control region. The UE may monitor the plurality ofPDCCHs. The PDCCH is transmitted on an aggregation of one or severalconsecutive control channel elements (CCEs). The CCE is a logicalallocation unit used to provide a coding rate for the PDCCH based on aradio channel state. The CCE corresponds to a plurality of resourceelement groups (REGs). A format and the number of bits for the PDCCH aredetermined by the number of CCEs. A base station determines a PDCCHformat according to DCI to be transmitted to the UE, and attaches acyclic redundancy check (CRC) to the control information. The CRC ismasked with a unique identifier (referred to as a radio networktemporary identifier (RNTI)) according to an owner or usage of thePDCCH. If the PDCCH is for a specific UE, a unique identifier (e.g.,cell-RNTI (C-RNTI)) of the UE may be masked to the CRC. Alternatively,if the PDCCH is for a paging message, a paging identifier (e.g.,paging-RNTI (P-RNTI)) may be masked to the CRC. If the PDCCH is forsystem information (more specifically, a system information block(SIB)), a system information RNTI (SI-RNTI) may be masked to the CRC.When the PDCCH is for a random access response, a random access-RNTI(RA-RNTI) may be masked to the CRC.

FIG. 4 illustrates an uplink subframe structure.

Referring to FIG. 4, an uplink subframe includes a plurality of (e.g. 2)slots. A slot may include different number of SC-FDMA symbols accordingto a CP length. The uplink subframe is divided into a control region anda data region in the frequency domain. The data region comprises a PUSCHand is used to carry a data signal such as audio data. The controlregion comprises a PUCCH and is used to carry uplink control information(UCI). The PUCCH includes an RB pair located at both ends of the dataregion in the frequency domain and hops in a slot boundary.

The PUCCH may be used to transmit the following control information.

-   -   Scheduling Request (SR): This information is used to request a        UL-SCH resource and is transmitted using an On-Off Keying (OOK)        scheme.    -   HARQ ACK/NACK: This is a response to a downlink data packet        (e.g. codeword) on a PDSCH and indicates whether the downlink        data packet has been successfully received. A 1-bit ACK/NACK        signal is transmitted as a response to a single downlink        codeword and a 2-bit ACK/NACK signal is transmitted as a        response to two downlink codewords. A HARQ response includes        positive ACK (simply, ACK), negative ACK (NACK), and DTX        (Discontinuous Transmission) or NACK/DTX. Here, the term        HARQ-ACK is used interchangeably with the term HARQ ACK/NACK or        ACK/NACK.    -   Channel State Information (CSI): This is feedback information        about a downlink channel. MIMO (Multiple Input Multiple        Output)-related feedback information includes a rank indicator        (RI) and a precoding matrix indicator (PMI). 20 bits per        subframe are used.

The quantity of control information (UCI) that a UE may transmit in asubframe depends on the number of SC-FDMA symbols available for controlinformation transmission. The SC-FDMA symbols available for controlinformation transmission means SC-FDMA symbols other than SC-FDMAsymbols used for transmitting reference signals. In the case of asubframe in which a Sounding Reference Signal (SRS) is configured, thelast SC-FDMA symbol of the subframe is excluded from the SC-FDMA symbolsavailable for control information transmission. A reference signal isused for coherent detection of a PUCCH. The PUCCH supports variousformats according to information transmitted thereon.

Table 3 shows the mapping relationship between PUCCH formats and UCI inLTE(−A).

TABLE 3 PUCCH format UCI (Uplink Control Information) Format 1 SR(Scheduling Request) (non-modulated waveform) Format 1a 1-bit HARQACK/NACK (SR exist/non-exist) Format 1b 2-bit HARQ ACK/NACK (SRexist/non-exist) Format 2 CSI (20 coded bits) Format 2 CSI and 1-bit or2-bit HARQ ACK/NACK (20 bits) (only in case of extended CP) Format 2aCSI and 1-bit HARQ ACK/NACK (20 + 1 coded bits) Format 2b CSI and 2-bitHARQ ACK/NACK (20 + 2 coded bits) Format 3 Up to 24-bit HARQ ACK/NACK +SR (LTE-A)

A description will be given of TDD signal transmission timing in asingle carrier (or cell) situation with reference to FIGS. 5 to 10.

FIGS. 5 and 6 illustrate PDSCH-UL ACK/NACK timing. Here, UL ACK/NACKmeans ACK/NACK transmitted on uplink, as a response to DL data (e.g.PDSCH).

Referring to FIG. 5, a UE may receive one or more PDSCH signals in M DLsubframes (SFs) (S502_0 to S502_M−1). Each PDSCH signal is used totransmit one or more (e.g. 2) transport blocks (TBs) according to atransmission mode. A PDCCH signal indicating release of SPS(Semi-Persistent Scheduling) may also be received in steps S502_0 toS502_M−1, which is not shown. When a PDSCH signal and/or a SPS releasePDCCH signal are present in the M DL subframes, the UE transmitsACK/NACK through in one UL subframe corresponding to the M DL subframes(S504) through a procedure for transmitting ACK/NACK (e.g. ACK/NACK(payload) generation, ACK/NACK resource allocation, etc.). ACK/NACKincludes acknowledgement information about the PDSCH signal and/or SPSrelease PDCCH received in step S502_0 to S502_M−1. While ACK/NACK istransmitted through a PUCCH basically, ACK/NACK is transmitted via aPUSCH when the PUSCH is transmitted at an ACK/NACK transmission time.Various PUCCH formats shown in Table 3 may be used for ACK/NACKtransmission. To reduce the number of ACK/NACK bits transmitted througha PUCCH format, various methods such as ACK/NACK bundling and ACK/NACKchannel selection may be used.

As described above, in TDD, ACK/NACK for data received at the M DLsubframes is transmitted through one UL subframe (i.e. M DL SF(s):1 ULSF) and the relationship therebetween is determined by a DASI (DownlinkAssociation Set Index).

Table 4 shows DASI (K: {k0, k1, . . . , k−1}) defined in LTE(−A). Table4 shows intervals between a UL subframe transmitting ACK/NACK and a DLsubframe associated with the UL subframe from the perspective of the ULsubframe. Specifically, when a PDCCH that indicates PDSCH transmissionand/or SPS (Semi-Persistent Scheduling) release is present in a subframen-k (k∈ K), the UE transmits ACK/NACK in a subframe n.

TABLE 4 TDD UL-DL Subframe n Configuration 0 1 2 3 4 5 6 7 8 9 0 — — 6 —4 — — 6 — 4 1 — — 7, 6 4 — — — 7, 6 4 — 2 — — 8, 7, 4, 6 — — — — 8, 7,4, 6 — — 3 — — 7, 6, 11 6, 5 5, 4 — — — — — 4 — — 12, 8, 7, 11 6, 5, 4,7 — — — — — — 5 — — 13, 12, 9, 8, 7, 5, 4, 11, 6 — — — — — — — 6 — — 7 75 — — 7 7 —

FIG. 6 illustrates a UL ACK/NACK transmission timing when UL-DLconfiguration #1 is configured. In the figure, each of SF#0 to #9 andSF#10 to #19 corresponds to a radio frame, and each numeral in blocksdenotes a UL subframe associated with a DL subframe from the perspectiveof the DL subframe. For example, ACK/NACK for a PDSCH of SF#5 istransmitted in SF#5+7 (=SF#12) and ACK/NACK for a PDSCH of SF#6 istransmitted in SF#6+6 (=SF#12). Accordingly, both ACKs/NACKs for DLsignals of SF#5/SF#6 are transmitted in SF#12. Similarly, ACK/NACK for aPDSCH of SF#14 is transmitted in SF#14+4 (=SF#18).

FIGS. 7 and 8 illustrate PHICH grant-PUSCH timing. A PUSCH may betransmitted corresponding to a PDCCH (UL grant) and/or a PHICH (NACK).

Referring to FIG. 7, a UE may receive a PDCCH (UL grant) and/or a PHICH(NACK) via a PDCCH (S702). Here, NACK corresponds to an ACK/NACKresponse to the previous PUSCH transmission. In this case, the UE mayinitially transmit/retransmit one or more transport blocks (TBs) througha PUSCH after k subframes (S704), through a procedure for PUSCHtransmission (e.g. TB coding, TB-CW swiping, PUSCH resource allocation,etc.). The present embodiment is based on the assumption of performing anormal HARQ operation in which a PUSCH is transmitted once. In thiscase, a PHICH and a UL grant corresponding to PUSCH transmission arepresent in the same subframe. However, in case of subframe bundling inwhich a PUSCH is transmitted multiple times through a plurality ofsubframes, a PHICH and a UL grant corresponding to PUSCH transmissionmay be present in different subframes.

Table 5 shows a UAI (Unlink Association Index) (k) for PUSCHtransmission in LTE(−A). Table 5 shows intervals between a DL subframewhere a PHICH/UL grant is detected and a UL subframe associated with theDL subframe from the perspective of the DL subframe. Specifically, whena PHICH/UL grant is detected in a subframe n, a UE may transmit a PUSCHin a subframe n+k.

TABLE 5 TDD UL-DL subframe number n Configuration 0 1 2 3 4 5 6 7 8 9 04 6 4 6 1 6 4 6 4 2 4 4 3 4 4 4 4 4 4 5 4 6 7 7 7 7 5

FIG. 8 illustrates a PUSCH transmission timing when UL-DL configuration#1 is configured. In the figure, each of SF#0 to #9 and SF#10 to #19corresponds to a radio frame, and each numeral in blocks denotes a ULsubframe associated with a DL subframe from the perspective of the DLsubframe. For example, a PUSCH corresponding to PHICH/UL grant of SF#6is transmitted in SF#6+6 (=SF#12) and a PUSCH corresponding to aPHICH/UL grant of SF#14 is transmitted in SF#14+4 (=SF#18).

FIGS. 9 and 10 illustrate a PUSCH-PHICH/UL grant timing. PHICH is usedto transmit DL ACK/NACK. Here, DL ACK/NACK means ACK/NACK transmitted ondownlink as a response to UL data (e.g. PUSCH).

Referring to FIG. 9, a UE transmits a PUSCH signal to a base station(S902). Here, the PUSCH signal is used to transmit one or more (e.g. 2)transport blocks (TBs) according to a transmission mode. The basestation may transmit ACK/NACK as a response to PUSCH transmission via aPHICH after k subframes (S904), through a procedure for ACK/NACKtransmission (e.g. ACK/NACK generation, ACK/NACK resource allocation,etc.). ACK/NACK includes acknowledgement information about the PUSCHsignal of the step S902. When a response to PUSCH transmission is NACK,the base station may transmit a UL grant PDCCH for PUSCH retransmissionto the UE after k subframes (S904). The present embodiment is based onthe assumption of performing a normal HARQ operation in which a PUSCH istransmitted once. In this case, a PHICH and UL grant used for PUSCHtransmission may be transmitted in the same subframe. In case ofsubframe bundling, however, the PHICH and UL grant used for PUSCHtransmission may be transmitted in different subframes.

Table 6 shows a UAI for PHICH/UL grant transmission in LTE(−A). Table 6shows intervals between a DL subframe in which a PHICH/UL grant ispresent and a UL subframe associated with the DL subframe from theperspective of the DL subframe. Specifically, a PHICH/UL grant of asubframe i corresponds to PUSCH transmission of a subframe i-k.

TABLE 6 TDD UL-DL subframe number i Configuration 0 1 2 3 4 5 6 7 8 9 07 4 7 4 1 4 6 4 6 2 6 6 3 6 6 6 4 6 6 5 6 6 6 4 7 4 6

FIG. 10 illustrates a PHICH/UL grant transmission timing when UL-DLconfiguration #1 is configured. In the figure, each of SF#0 to #9 andSF#10 to #19 corresponds to a radio frame, and each numeral in blocksdenotes a DL subframe associated with a UL subframe. For example, aPHICH/UL grant corresponding to a PUSCH of SF#2 is transmitted in SF#2+4(=SF#6) and a PHICH/UL grant corresponding to a PUSCH of SF#8 istransmitted in SF#8+6 (=SF#14).

FIG. 11 illustrates a communication system for carrier aggregation (CA).A LTE-A system employs carrier aggregation (or bandwidth aggregation)technology which aggregates a plurality of uplink/downlink frequencyblocks to obtain a wider uplink/downlink bandwidth. Each frequency blockis transmitted using a component carrier (CC). The CC may be construedas a carrier frequency (or center carrier, center frequency) for thecorresponding frequency block.

Referring to FIG. 11, a plurality of uplink/downlink CCs may beaggregated to support a wider uplink/downlink bandwidth. The CCs may becontiguous or non-contiguous in the frequency domain. A bandwidth ofeach component carrier may be independently determined. Asymmetricalcarrier aggregation is possible, in which the number of UL CCs isdifferent from the number of DL CCs may be implemented. For example,when there are two DL CCs and one UL CC, the DL CCs and UL CC may beconfigured to be in 2:1 correspondence. A DL CC/UL CC link may be fixedor semi-statically configured in the system. Even if the entire systembandwidth is configured with N number of CCs, a frequency band where aspecific UE can monitor/receive may be limited to M (<N) number of CCs.Various parameters for carrier aggregation may be configuredcell-specifically, UE-group-specifically, or UE-specifically. Controlinformation may be transmitted/received only via a specific CC. Thisspecific CC may be referred to as a Primary CC (PCC) (or anchor CC) andthe other CCs may be referred to as Secondary CCs (SCCs).

In LTE-A, the concept of a cell is used to manage radio resources. Acell is defined as a combination of downlink resource and uplinkresource. Yet, the uplink resource is not mandatory. Therefore, a cellmay be composed of downlink resource only or both downlink resource anduplink resource. The linkage between a carrier frequency (or DL CC) ofdownlink resource and a carrier frequency (or UL CC) of uplink resourcemay be indicated by system information. A cell operating in primaryfrequency resource (or PCC) may be referred to as a primary cell (PCell)and a cell operating in secondary frequency resource (or a SCC) may bereferred to as a secondary cell (SCell). The PCell is used for a UE toperform a procedure for initial connection establishment or a procedurefor connection re-establishment. The PCell may refer to a cell operatingon a DL CC SIB2-linked to a UL CC. Furthermore, the PCell may refer to acell indicated during handover. The SCell may be configured after RRCconnection establishment and may be used to provide additional radioresource. The PCell and the SCell may collectively be referred to as aserving cell. Accordingly, there exists a single serving cell composedof a PCell only for a UE in an RRC_Connected state for which carrieraggregation is not configured or which does not support CA. On the otherhand, there exist one or more serving cells including a PCell and entireSCells for a UE in an RRC CONNECTED state, for which carrier aggregationis configured. For carrier aggregation, a network may configure one ormore SCells in addition to an initially configured PCell, for a UEsupporting carrier aggregation during a procedure for connectionestablishment after a procedure for initial security activation isinitiated.

FIG. 12 illustrates scheduling when a plurality of carriers isaggregated. It is assumed that 3 DL CCs are aggregated and DL CC A isset to a PDCCH CC. Each of DL CC A, DL CC B and DL CC C may be referredto as a serving CC, serving carrier, serving cell, etc. In case of CIF(Carrier Indicator Field) disabled, each DL CC may transmit only a PDCCHthat schedules a PDSCH of the DL CC itself without a CIF (non-cross-CCscheduling). When the CIF is enabled by UE-specific (orUE-group-specific or cell-specific) higher layer signaling, a specificCC (e.g. DL CC A) may carry not only a PDCCH that schedules the PDSCH ofthe DL CC A but also PDCCHs that schedule PDSCHs of other DL CCs usingthe CIF (cross-CC scheduling). A PDCCH is not transmitted in DL CC B/C.Here, a specific CC (or cell) used to transmit a PDCCH is called ascheduling CC (or scheduling cell). The term scheduling CC (or cell) maybe used interchangeably with the term PDCCH monitoring CC (or PDCCHmonitoring cell). A CC (or cell) in which a PDSCH/PUSCH is scheduled bya PDCCH of another CC is called a scheduled CC (or scheduled cell). Oneor more scheduling CCs may be configured for one UE. A scheduling CCincludes a PCC. When only one scheduling CC is configured, thescheduling CC corresponds to the PCC. The scheduling CC may beconfigured UE-specifically, UE group-specifically or cell-specifically.

A conventional CA TDD system only considers a case in which eachaggregated CC has the same UL-DL configuration. In this case, a TDDsignal transmission timing in a single cell situation, described withreference to FIGS. 5 to 10, may be used because all CCs have the sameDL/UL subframe timing. However, a scheme for independently setting UL-DLconfigurations for respective CCs in consideration of a UL/DL loaddifference and a channel state difference between CCs is underdiscussion recently. However, if a plurality of CCs has different UL-DLconfigurations when cross-CC scheduling is applied, the followingproblem may be encountered in relation to signal transmission/receptiontimings.

A CC carrying data and ACK/NACK for the data may be determined based onthe following criteria in a cross-CC scheduling situation.

-   -   PDSCH/PUSCH: CC indicated by a CIF of a PDCCH detected from a        scheduling CC    -   DL ACK/NACK (e.g. PHICH): scheduling CC (e.g. DL PCC)    -   UL ACK/NACK (e.g. PUCCH): UL PCC

As described above, a CC carrying a signal is determined by apredetermined rule according to signal type. If all CCs have the sameUL-DL configuration, there is no problem for signal transmissionaccording to the above-described criteria. However, when UL-DLconfigurations are independently given per CCs and thus the CCs havedifferent UL-DL configurations, there occurs a problem in signaltransmission/reception because DL/UL subframes available for the CCs aredifferent. Furthermore, it may be necessary to define new UL/DL ACK/NACKtiming and/or DL/UL grant timing.

To solve the above-described problem, the present invention proposes amethod of configuring a signal transmission timing (e.g. UL ACK/NACKtransmission timing, UL grant transmission timing and DL ACK/NACKtransmission timing) in a system supporting CA and TDD. In case of ULACK/NACK, the following proposed method may be applied irrespective ofnon-cross-CC scheduling and cross-CC scheduling. In case of ULgrant/PHICH, the method proposed hereinafter may be applied only when across-CC scheduling mode is configured or cross-CC scheduling isactually performed. For example, when a scheduling CC schedules onlyitself (i.e. non-cross-CC scheduling) even though a cross-CC schedulingmode has been configured, the method proposed hereinafter may not beused. In this case, the conventional TDD signal transmission timingconfigured for the scheduling CC may be applied.

Embodiments of the present invention will now be described on theassumption that 2 CCs (i.e. a PCC and a SCC) having different UL-DLconfigurations are aggregated. However, the embodiments of the presentinvention may be applied to a case in which three or more CCs havingdifferent UL-DL configurations are aggregated. In the followingdescription, the PCC and SCC may be construed according to the originaldefinition, or may be construed as a scheduling CC and a scheduled CC,respectively. For example, the PCC and SCC may mean a PCC and SCC incase of UL ACK/NACK, whereas the PCC and SCC may mean a scheduling CCand a scheduled CC in case of UL grant/PHICH. In addition, D denotes aDL subframe, S denotes a special subframe, and U denotes a UL subframein the following description. It is assumed that S is used as D or Uand, unless otherwise specified, it is used as D. In the followingdescription, the term CC is used interchangeably with the term cell (orserving cell) and the term PCC and SCC may be respectively usedinterchangeably with the term PCell and an SCell.

Embodiment 1: UL ACK/NACK Timing

The present embodiment proposes a scheme for transmitting uplink controlinformation (e.g. UL ACK/NACK) in an environment in which a plurality ofCCs having different UL-DL configurations are aggregated for a UEoperating in TDD. In consideration of a situation in which a pluralityof CCs having different TDD UL-DL configurations are aggregated for theUE and UL ACK/NACK is transmitted via only one CC, it is necessary todefine a scheme for feeding back UL ACK/NACK information via one CCregarding data (e.g. PDSCHs) received on a plurality of CCs.

The proposals of the present embodiment are summarized as follows.

Rule 1-1: UL ACK/NACK Transmission Subframe

When a plurality of CCs having different UL-DL configurations areaggregated for a UE, UL ACK/NACK may be transmitted only in a subframein which all the CCs aggregated for the UE are configured as UL, or in asubset (part) of the subframe. When a subframe (determined using a DASI(Downlink Association Set Index) of the corresponding CC or a specificCC), which is associated with the subframe in which all the CCs areconfigured as UL, is not configured as DL for all the CCs (e.g. PCC: U,SCC: D), the UE may skip decoding of PDSCH in the correspondingsubframe. Accordingly, a HARQ-ACK response for the correspondingsubframe may not be included in a HARQ-ACK payload.

Rule 1-2: DASI (Downlink Association Set Index)

A DASI (refer to Table 4) of a CC having a larger number of DL subframesis commonly applied to all the aggregated CCs. Equivalently, a DASI of aCC having a smaller number of UL subframes is commonly applied to allaggregated CCs.

*Rules 1-1 and 1-2 describe that the proposed method is applied to allthe aggregated CCs when some of the CCs have different UL-DLconfigurations. However, Rules 1-1 and 1-2 may be modified such that theproposed method is applied to a SCC corresponding to UL ACK/NACK (i.e. aCC carrying a PDSCH corresponding to UL ACK/NACK) only when UL-DLconfiguration of the SCC is different from UL-DL configuration of thePCC, but otherwise the conventional scheme is applied to determine ULACK/NACK timing.

FIGS. 13 and 14 illustrate a UL ACK/NACK timing configuration schemeaccording to the present embodiment.

Referring to FIG. 13, it is assumed that a PCC having UL-DLconfiguration #0 and a SCC having UL-DL configuration #1 are configuredfor a UE. UL ACK/NACK is transmitted via the PCC. According to Rule 1-1,UL ACK/NACK may be transmitted only in subframes (subframes #2/#3/#7/#8)in which both the PCC and SCC are configured as UL, or in a subset ofthe subframes, from among UL subframes of the PCC. That is, subframes#4/#9 of the PCC are not used for UL ACK/NACK transmission. The methodaccording to the present embodiment may be applied to only a case inwhich cross-CC scheduling from the PCC to the SCC occurs.

According to Rule 1-2, DL subframes associated with subframes#2/#3/#7/#8 of the PCC are determined by a DASI of the SCC (i.e. UL-DLconfiguration #1) (FIG. 14). This is because the number of DL subframesof the SCC is greater than the number of DL subframes of the PCC,equivalently, the number of UL subframes of the SCC is less than thenumber of UL subframes of the PCC.

Accordingly, the UE may determine a ACK/NACK payload for the two CCs ora DL subframe that needs to be fed back, by commonly applying the DASIof the SCC to the two CCs when UL ACK/NACK is transmitted on the PCC. IfDASI (k) of UL-DL configuration #1 indicates a UL subframe in FIG. 14,UL ACK/NACK for the corresponding UL subframe may not be added to anACK/NACK payload. That is, the corresponding subframe may not beconsidered during UL ACK/NACK transmission. In a normal case, the sizeof UL ACK/NACK payload is determined according to the number of DLsubframes according to a DASI, the number of aggregated (or activated)CCs, a transmission mode of the corresponding subframe. Alternatively,in order to reduce UL ACK/NACK detection error caused by change of thesize of ACK/NACK payload, when a subframe indicated by DASI (k) is a ULsubframe, ACK/NACK for the corresponding subframe may be set to NACK/DTXto maintain the size of ACK/NACK payload constant.

According to the proposed method, it is possible to utilize theconventional UL ACK/NACK timing (e.g. DASI) without defining new ULACK/NACK timing when a plurality of CCs having different UL-DLconfigurations is aggregated.

Embodiment 2: DL ACK/NACK (or UL Grant) Timing

The present embodiment proposes a scheme for transmitting downlinkcontrol information (e.g. DL ACK/NACK) in an environment in which aplurality of CCs having different UL-DL configurations are aggregatedfor a UE operating in TDD. In consideration of a situation in which aplurality of CCs having different TDD UL-DL configurations areaggregated for the UE and DL ACK/NACK is transmitted via only ascheduling CC, it is necessary to define a scheme for feeding back DLACK/NACK information via one CC regarding data (e.g. PUSCHs) received ona plurality of CCs.

While the following description is focused on DL ACK/NACK (e.g. PHICH)for convenience, the present invention is equally/similarly applied to acase in which a UL grant (e.g. PDCCH) is transmitted.

The proposals of the present embodiment are summarized as follows.

Rule 2-1: DL ACK/NACK Transmission Subframe

When a plurality of CCs having different UL-DL configurations areaggregated for a UE, DL ACK/NACK may be transmitted only in a subframein which all the CCs aggregated for the UE are configured as DL, or in asubset (part) of the subframe. When a subframe (determined using a UAI(Uplink Association Index) of the corresponding CC or a specific CC),which is associated with the subframe in which all the CCs areconfigured as DL, is not configured as UL for all the CCs (e.g. PCC: D,SCC: U), PUSCH related scheduling (e.g. UL grant)/feedback (e.g. PHICHtransmission) may be skipped in the corresponding subframe.

Rule 2-2: UAI (Uplink Association Index)

A UAI (refer to Table 6) of a CC having a larger number of UL subframesis commonly applied to all the aggregated CCs. Equivalently, a UAI of aCC having a smaller number of DL subframes is commonly applied to allthe aggregated CCs.

*Rules 2-1 and 2-2 describe that the proposed method is applied to allthe aggregated CCs when some of the CCs have different UL-DLconfigurations. However, Rules 2-1 and 2-2 may be modified such that theproposed method is applied to a scheduled CC corresponding to DLACK/NACK (i.e. a CC on which a PUSCH corresponding to DL ACK/NACK isreceived) (e.g. SCC) only when UL-DL configuration of the scheduled CCis different from UL-DL configuration of a scheduling CC (e.g. PCC), butotherwise the conventional scheme is applied to determine ACK/NACKtiming.

FIGS. 15 and 16 illustrate a DL ACK/NACK timing configuration schemeaccording to the present embodiment. Here, the PCC corresponds to ascheduling CC and the SCC corresponds to a scheduled CC.

Referring to FIG. 15, it is assumed that the PCC having UL-DLconfiguration #1 and the SCC having UL-DL configuration #2 areconfigured for a UE. DL ACK/NACK is transmitted through the PCC.According to Rule 2-1, DL ACK/NACK may be transmitted only in subframes(subframes #0/#1/#4/#5/#6/#9) in which both the PCC and SCC areconfigured as DL, or a subset of the subframes, from among DL subframesof the PCC. Accordingly, although subframes #3/#8 of the SCC correspondto DL subframes, DL ACK/NACK is not transmitted in the correspondingsubframes. The method according to the present embodiment may be appliedonly to a case in which cross-CC scheduling from the PCC to the SCCoccurs.

According to Rule 2-2, UL subframes associated with subframes#0/#1/#4/#5/#6/#9 of the PCC are determined by a UAI of the PCC (i.e.UL-DL configuration #1) (FIG. 16). This is because the number of ULsubframes of the PCC is greater than the number of UL subframes of theSCC, equivalently, the number of DL subframes of the PCC is smaller thanthe number of DL subframes of the SCC.

Accordingly, the UE may determine DL ACK/NACK for the two CCs or a ULsubframe that needs to be fed back, by commonly applying the UAI of thePCC to the two CCs when DL ACK/NACK is transmitted on the PCC. If UAI(k) of UL-DL configuration #1 indicates a DL subframe in FIG. 15, DLACK/NACK for the corresponding DL subframe is not transmitted. Since aPHICH is individually transmitted for each PUSCH, no PUSCH transmissionmeans UL DTX (Discontinuous Transmission). Furthermore, since a PHICHresource uses a PRB index used for PUSCH transmission, the PHICHresource is not allocated when PUSCH transmission is not performed.

According to the proposed method, it is possible to utilize theconventional DL ACK/NACK timing (e.g. UAI) without defining new DLACK/NACK timing when a plurality of CCs having different UL-DLconfigurations is aggregated.

Embodiment 3: Nested Carrier Aggregation

As described with reference to FIG. 11, when a plurality of CCs isaggregated, cross-CC scheduling is performed only through a specific CC(e.g. PCC) or UCI is transmitted through only a specific CC. In thiscase, if a plurality of CCs having different UL-DL configurations issimply aggregated, it is necessary to define a new timing relationship,which is not defined in LTE(−A), such as DL/UL ACK/NACK timing and/orDL/UL grant timing.

FIG. 17 illustrates a case in which new signal transmission timing isrequired. The present embodiment is based on the assumption that the PCChas UL-DL configuration #2 and the SCC has UL-DL configuration #4. Forexample, the PCC corresponds to a DL subframe and the SCC corresponds toa UL subframe in subframe #3, and thus cross-CC scheduling from the PCCto the SCC is limited. Accordingly, new grant timing and new PHICHtiming need to be defined.

To solve the above-mentioned problem, the present embodiment proposes amethod for using the existing UL/DL ACK/NACK timing and DL/UL granttiming by limiting combinations of UL-DL configurations of CCs when aplurality of CCs are aggregated. The method according to the presentembodiment may support cross-CC scheduling via a specific CC only (e.g.PCC) or transmission of UAI via a specific CC only.

Specifically, the following scheme is proposed when a plurality of TDDCCs are aggregated.

1. When uplink/downlink control information is transmitted only on aPCC, combinations of UL-DL configurations of CCs may be limited suchthat a UL subframe set of the PCC includes a UL subframe set of a SCC(referred to as a UL nested structure for convenience)

a. UL grant timing is determined based on the PCC. That is, UL granttiming of the PCC may be commonly applied to all CCs.

b. PHICH timing is determined based on the PCC. That is, PHICH timing ofthe PCC may be commonly applied to all CCs.

c. UL ACK/NACK timing is determined based on the SCC (when only two CCsare aggregated). That is, UL ACK/NACK timing of the SCC may be commonlyapplied to all CCs. Alternatively, UL ACK/NACK timing of each CC may beapplied as it is. Even in this case, ACK/NACK for a PDSCH of the SCC maybe transmitted in a UL subframe of the PCC because UL subframes of theSCC are included in those of the PCC.

2. When the UL subframe set of the PCC does not include the UL subframeset of the SCC, uplink/downlink control information is not transmittedonly on the PCC. That is, cross-CC scheduling may not be performed, aPHICH may be transmitted for each CC, or UL ACK/NACK or CSI may betransmitted on all CCs.

FIG. 18 illustrates a nested carrier aggregation scheme according to anembodiment of the present invention. Here, the PCC corresponds to ascheduling CC and the SCC corresponds to a scheduled CC. The presentembodiment is based on the assumption that the PCC has UL-DLconfiguration #1 and the SCC has UL-DL configuration #2. In this case,it is advantageous in that if uplink/downlink control signal istransmitted only on the PCC, it is possible to utilize the conventionaltiming defined in LTE(−A) intact without introducing new UL grant timingand DL ACK/NACK timing (e.g. PHICH timing). That is, it is advantageousin that UL grant timing of the SCC may utilize UL grant timing of thePCC intact and PHICH timing of the SCC may utilize PHICH timing of thePCC intact. Furthermore, it is advantageous in that as described inembodiment 1, UL ACK/NACK timing may utilize the configuration of theSCC intact. In addition, UL ACK/NACK timing for each CC may be appliedutilize. Even in this case, ACK/NACK for a PDSCH of the SCC may betransmitted in a UL subframe of the PCC because UL subframes of the SCCis included in those of the PCC.

FIG. 19 illustrates a nested carrier aggregation scheme according to anembodiment of the present invention. In FIG. 19, subframe configurationaccording to UL-DL configuration is as defined in Table 1. When two CCsare aggregated, a total of 49 combinations of UL-DL configurations arepossible if there is no limitation on the combination of UL-DLconfigurations. However, in case of nested carrier aggregation, thenumber of available combinations of UL-DL configurations is reduced to25.

Alternatively, the following scheme may be considered to commonly applyPCC timing for UL ACK/NACK transmission.

1. When uplink/downlink control information is transmitted only on aPCC, combinations of UL-DL configurations of CCs may be limited suchthat a DL subframe set of the PCC includes a DL subframe set of a SCC(referred to as a DL nested structure for convenience).

a. UL grant timing is determined based on a specific CC. For example, ULgrant timing of the PCC may be applied. Preferably, scheduling for aPUSCH of the SCC may be limited in a subframe in which the PCCcorresponds to D and the SCC corresponds to U. Furthermore, one DLsubframe needs to schedule a plurality of UL subframes in order toschedule a subframe in which the PCC corresponds to D and the SCCcorresponds to U. In this case, a UL subframe indicator (USI) field thatindicates one of a plurality of UL subframes may be implicitly orexplicitly present in a scheduling PDCCH.

b. (When only two CCs are aggregated) UL ACK/NACK timing of a specificCC is applied. For example, UL ACK/NACK timing of the PCC may becommonly applied to all CCs.

c. PHICH timing is determined based on a specific CC. For example, PHICHtiming of the PCC may be commonly applied to all CCs

2. When the DL subframe set of the PCC does not include the DL subframeset of the SCC, uplink/downlink control information is not transmittedonly on the PCC. That is, cross-CC scheduling may not be performed, aPHICH may be transmitted for each CC, or UL ACK/NACK or CSI may betransmitted on all CCs.

FIG. 20 illustrates a nested carrier aggregation scheme according to anembodiment of the present invention. In FIG. 20, subframe configurationaccording to UL-DL configuration is as defined in Table 1. When two CCsare aggregated, a total of 49 combinations of UL-DL configurations arepossible if there is no limitation on the combination of UL-DLconfigurations. However, in case of nested carrier aggregation, thenumber of combinations of UL-DL configurations available is reduced to25.

FIG. 21 illustrates a base station and a UE applicable to an embodimentof the present invention. When a wireless communication system includesa relay, communication is performed between a base station and the relayon a backhaul link and between the relay and a UE on an access link. Thebase station or UE shown in the figure may be replaced by a relay asnecessary.

Referring to FIG. 21, an wireless communication system includes a basestation (BS) 110 and a UE 120. The base station 110 includes a processor112, a memory 114 and an RF (Radio Frequency) unit 116. The processor112 may be configured to implement the procedures and/or methodsproposed by the present invention. The memory 114 is connected to theprocessor 112 and stores various types of information relating tooperations of the processor 112. The RF unit 116 is connected to theprocessor 112 and transmits and/or receives RF signals. The UE 120includes a processor 122, a memory 124 and an RF unit 126. The processor122 may be configured to implement the procedures and/or methodsproposed by the present invention. The memory 124 is connected to theprocessor 122 and stores various types of information relating tooperations of the processor 122. The RF unit 126 is connected to theprocessor 122 and transmits and/or receives RF signals. The BS 110 andthe UE 120 may have a single antenna or multiple antennas.

The embodiments of the present invention described hereinbelow arecombinations of elements and features of the present invention. Theelements or features may be considered selective unless otherwisementioned. Each element or feature may be practiced without beingcombined with other elements or features. Further, an embodiment of thepresent invention may be constructed by combining parts of the elementsand/or features. Operation orders described in embodiments of thepresent invention may be rearranged. Some constructions of any oneembodiment may be included in another embodiment and may be replacedwith corresponding constructions of another embodiment. It is obvious tothose skilled in the art that claims that are not explicitly cited ineach other in the appended claims may be presented in combination as anembodiment of the present invention or included as a new claim by asubsequent amendment after the application is filed.

In the embodiments of the present invention, a description is made,centering on a data transmission and reception relationship between a BSand a UE. In some cases, a specific operation described as performed bythe BS may be performed by an upper node of the BS. Namely, it isapparent that, in a network comprised of a plurality of network nodesincluding a BS, various operations performed for communication with anMS may be performed by the BS, or network nodes other than the BS. Theterm eNB' may be replaced with the term ‘fixed station’, ‘Node B’,‘eNode B (eNB)’, ‘access point’, etc. The term ‘UE’ may be replaced withthe term ‘Mobile Station (MS)’, ‘Mobile Subscriber Station (MSS)’,‘mobile terminal’, etc.

The embodiments of the present invention may be achieved by variousmeans, for example, hardware, firmware, software, or a combinationthereof. In a hardware configuration, the methods according to theembodiments of the present invention may be achieved by one or moreApplication Specific Integrated Circuits (ASICs), Digital SignalProcessors (DSPs), Digital Signal Processing Devices (DSPDs),Programmable Logic Devices (PLDs), Field Programmable Gate Arrays(FPGAs), processors, controllers, microcontrollers, microprocessors,etc.

In a firmware or software configuration, the embodiments of the presentinvention may be implemented in the form of a module, a procedure, afunction, etc. For example, software code may be stored in a memory unitand executed by a processor. The memory unit is located at the interioror exterior of the processor and may transmit and receive data to andfrom the processor via various known means.

Those skilled in the art will appreciate that the present invention maybe carried out in other specific ways than those set forth hereinwithout departing from the spirit and essential characteristics of thepresent invention. The above embodiments are therefore to be construedin all aspects as illustrative and not restrictive. The scope of theinvention should be determined by the appended claims and their legalequivalents, not by the above description, and all changes coming withinthe meaning and equivalency range of the appended claims are intended tobe embraced therein.

INDUSTRIAL APPLICABILITY

The present invention is applicable to wireless communicationapparatuses such as a UE, a relay, a base station, etc.

1. A method for transmitting uplink control information by a userequipment in a time division duplex (TDD) wireless communication systemconfigured with a plurality of serving cells, the method comprising:receiving at least one downlink signal in at least one subframe, the atleast one downlink signal requiring a hybrid automatic repeat requestacknowledgement (HARQ-ACK) response; and transmitting the HARQ-ACKresponse to the at least one downlink signal on one of the plurality ofserving cells, wherein when the plurality of serving cells havedifferent uplink-downlink (UL-DL) configurations, the HARQ-ACK responseis transmitted only in an uplink subframe which is configured as uplinkfor all the plurality of serving cells and is associated with the atleast one subframe.
 2. The method of claim 1, wherein the at least onedownlink signal is received on the plurality of serving cells.
 3. Themethod of claim 1, wherein when the at least one subframe is a subframen-k and the uplink subframe is a subframe n, k is given by a followingtable: UL-DL Subframe number Configuration 0 1 2 3 4 5 6 7 8 9 0 — — 6 —4 — — 6 — 4 1 — — 7, 6 4 — — — 7, 6 4 — 2 — — 8, 7, 4, 6 — — — — 8, 7,4, 6 — — 3 — — 7, 6, 11 6, 5 5, 4 — — — — — 4 — — 12, 8, 7, 11 6, 5, 4,7 — — — — — — 5 — — 13, 12, 9, 8, 7, 5, 4, 11, 6 — — — — — — — 6 — — 7 75 — — 7 7 —


4. The method of claim 2, wherein the plurality of serving cellscomprises a primary cell and a secondary cell, and wherein the HARQ-ACKresponse is transmitted on the primary cell.
 5. The method of claim 4,wherein the HARQ-ACK response is transmitted via a physical uplinkcontrol channel (PUCCH) of the primary cell.
 6. The method of claim 1,wherein the at least one downlink signal includes a physical downlinkshared channel (PDSCH) signal or a physical downlink control channel(PDCCH) signal indicating semi-persistent scheduling (SPS) release.
 7. Auser equipment configured to transmit uplink control information in atime division duplex (TDD) wireless communication system configured witha plurality of serving cells, the user equipment comprising: a radiofrequency (RF) unit; and a processor, wherein the processor isconfigured to: receive at least one downlink signal in at least onesubframe, the at least one downlink signal requiring a hybrid automaticrepeat request acknowledgement (HARQ-ACK) response, and transmit theHARQ-ACK response to the at least one downlink signal on one of theplurality of serving cells, wherein when the plurality of serving cellshave different uplink-downlink (UL-DL) configurations, the HARQ-ACKresponse is transmitted only in an uplink subframe which is configuredas uplink for all the plurality of serving cells and is associated withthe at least one subframe.
 8. The user equipment of claim 7, wherein theat least one downlink signal is received on the plurality of servingcells.
 9. The user equipment of claim 7, wherein when the at least onesubframe is a subframe n-k and the uplink subframe is a subframe n, k isgiven by a following table: UL-DL Subframe number Configuration 0 1 2 34 5 6 7 8 9 0 — — 6 — 4 — — 6 — 4 1 — — 7, 6 4 — — — 7, 6 4 — 2 — — 8,7, 4, 6 — — — — 8, 7, 4, 6 — — 3 — — 7, 6, 11 6, 5 5, 4 — — — — — 4 — —12, 8, 7, 11 6, 5, 4, 7 — — — — — — 5 — — 13, 12, 9, 8, 7, 5, 4, 11, 6 —— — — — — — 6 — — 7 7 5 — — 7 7 —


10. The user equipment of claim 8, wherein the plurality of servingcells comprises a primary cell and a secondary cell, and wherein theHARQ-ACK response is transmitted on the primary cell.
 11. The userequipment of claim 10, wherein the HARQ-ACK response is transmitted viaa physical uplink control channel (PUCCH) of the primary cell.
 12. Theuser equipment of claim 7, wherein the at least one downlink signalincludes a physical downlink shared channel (PDSCH) signal or a physicaldownlink control channel (PDCCH) signal indicating semi-persistentscheduling (SPS) release.